Toothbrushes typically have a head with a plurality of tooth cleaning elements, such as for example bristle filaments and elastomeric elements, attached to the head for cleaning teeth, removing bacterial plaque, and stimulating gums. It is desirable to have a toothbrush that removes plaque and is gentle on the soft tissue in the oral cavity. There are a number of tests to assess the amount of plaque removed by a toothbrush, however, there are no well-known defined objective tests for determining the gentleness of a toothbrush.
In addition, certain tooth cleaning elements are more gentle than others. For example, toothbrush bristle filaments with acceptably rounded ends allow for efficient removal of bacterial plaque and are less harmful to soft tissue in the oral cavity than non-rounded bristle filaments, or poorly rounded bristle filaments. Studies have shown that gingival abrasion is affected by filament endrounding. Assessment of endrounding on toothbrush bristle filaments is typically conducted through microscopy and visually comparing the magnified images of test bristle filaments to bristle filaments having known shapes and degrees of endrounding. Microscopy is labor intensive and time consuming because toothbrushes often have over a thousand bristle filaments. In addition, microscopy cannot effectively visually demonstrate the gentleness of the toothbrush to a consumer.